The inventive concept relates generally to flash memory devices and programming methods for flash memory devices. More particularly, the inventive concept relates to flash memory devices and methods providing improved programming speed.
Semiconductor memory devices may be classified as volatile or nonvolatile according to their operating characteristics. Volatile memory devices perform read/write operations at high speed but stored data is lost in the absence of applied power. In contrast, nonvolatile memory devices are able to retain stored data in the absence of applied power. So-called “flash memory” is one type of nonvolatile memory that provides exceptional memory cell integration density. As such, flash memory has been widely adopted for use as bulk data storage media and within contemporary memory systems.
Where flash memory cells were once limited to binary data, emerging flash memory cells are capable of storing multiple data bits (i.e., 2 or more), However, the programming of multiple data bits in flash memory requires careful control over the threshold voltage distributions that respectively correspond to programmed data values. For example, coupling between proximate memory cells may cause shifting or expansion of threshold voltage distributions. Such shifting and/or expansion of threshold voltage distribution(s) erodes read margins, thereby leading to read data errors.